This invention relates to certain compositions and articles containing a polymer of a vinyl aromatic aminimide. More particularly, it relates to compositions and articles incorporating polymeric aminimides which exhibit thermoreversible gel-forming properties and negative thixotropy.
Polymeric aminimides and their production have been reported in the chemical literature and described in patents. For example, vinyl aromatic aminimides and polymers thereof are described in the publication of B. M. Culbertson et al., Journal of Polymer Science: PART A-1, Vol. 6, 2197-2207 (1968); and in U.S. Pat. No. 3,641,145 (issued Feb. 8, 1972 to B. M. Culbertson et al.). These polymers contain the aminimide moiety ##STR1## and are described in the aforementioned patent as being soluble in water. The polymers are disclosed as having utility in the formation of polyurethanes based on the ability of the polymeric aminimides to be converted to polyisocyanates.
It has been found that the polymeric vinyl aromatic aminimides, e.g., poly (trimethylamine-4-vinylbenzimide), exhibit unusual rheological properties in an aqueous medium such that the polymers can be employed to advantage where such properties are desireably utilized. For example, it has been discovered that a polymer of trimethylamine-4-vinyl-benzimide at a 5% wt. concentration in water forms a thermoreversible gel. Negative thixotropy is exhibited where, for example, the polymer is present at a concentration of about 2.5% by weight.